[FFmpeg-user] H264 residuals after decoding avcodec_decode_video2

dasara shullani shullani.dasara at gmail.com
Thu May 26 17:52:32 CEST 2016

Hi everyone,
i'm new to the ffmpeg community, but I'm trying to implement a
c-application that uses the ffmpeg libraries (ffmpeg 3.0) in order to print
out qp, mb_type and dct_coeff  for each MB/frame.
As far as I know, those info are available from CLI, using -debug flag,
indeed I
used that flag for an H.262 video stream.
My main problem is to extract dct_coeffs, from an H.264 stream, during the
decoding process.

In this mailing-list I found out an old post, that suggested to look for
the h264_cabac.c file
and the decode_cabac_residual_internal() function and consequently the
ff_h264_decode_mb_cabac(). Unfortunately I was not able to find a solution
to my problem.

Is there a variable in H264Context or AVCodecContext (or somewhere else)
that stores the residual values for each frame?
In order to further clarify my request, I would like to obtain, after the
entropy decoder process, the dequantized residuals  or idct residuals, if
they are stored.


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